1. Field of the Invention
This invention relates to a thermal management system. More particularly, the invention relates to a thermal management system for cooling electronic equipment on a space vehicle.
2. Description of the Related Art
Heat generated by electronic equipment on a space vehicle can damage critical components if not removed from the vehicle. Typically, radiators that face the cold sink of space are used to remove this heat. The heat generated by electronic equipment disposed on a common mounting plate is transferred to a radiator via heat pipes.
One proposal for the mounting of electronic equipment in a space vehicle is shown in FIG. 1, in which the spacecraft is designated generally by reference numeral 10. Spacecraft 10 is comprised of a plurality (eight in FIG. 1) of T-shaped pallets 12, each of which includes a radiator panel 14 and a mounting panel 16. The radiator panels 14 of pallets 12 are connected end to end to enclose an interior space 18 including mounting panels 16. Pieces of electronic equipment 20 are mounted on mounting panels 16, and heat generated by electronic equipment 20 is transferred to radiator panels 14 by L-shaped heat pipes 22.
The pattern of heat flow in the system of spacecraft 10 is depicted in FIG. 1 with reference to representative pallet 12a. . Heat (arrows Q.sub.in) generated in electronic equipment 20a is transferred to mounting plate 16a, which preferably is comprised of a material having high thermal conductivity. The heat then is conducted from mounting plate 16a by heat pipes 22a to radiator panel 14a. Arrows Qout represent heat transfer from radiator panel 14a to the cold sink of space.
Although the T-pallet construction shown in FIG. 1 provides an efficient arrangement for electronic equipment 20, cooling problems arise when radiator panel 14a, for example, faces the sun. In such an orientation, radiator panel 14a must be shut down to prevent absorption of solar energy into electronic equipment 20a mounted on mounting plate 16a. Typically, radiator panel 14a is shut down by expanding a control gas into the portion of heat pipes 20a mounted on radiator panel 14a. With the heat flow between radiator panel 14a and electronic equipment 20a shut down, however, there is no way for heat generated within electronic equipment 20a to be removed through radiator panel 14a.
One prior attempt at solving the problem of cooling electronic equipment in the portion of a spacecraft facing the sun incorporates steerable radiators. This approach minimizes the radiator's exposure to the sun by orienting the radiator away from the sun with rotating mounting arms. In this type of system, additional mechanical equipment, with its attendant cost and weight penalties, is required. In addition, surface area is wasted because the radiators are not mounted to the surface of the vehicle itself.
Another proposed solution to the solar exposure problem is thermal storage, in which a material having a low melting point is used to provide phase-change heat transfer to remove the heat generated by the electronic equipment mounted on the T-pallets facing the sun. The drawbacks to this proposal include difficulty in designing the phase-change material system with the vehicle's orbit and time of sun exposure, weight penalties associated with the thermal storage material, and the possibility of equipment contamination from the thermal storage material.
The present invention is intended to provide a thermal management system for cooling a spacecraft's electronic equipment arranged on interconnected T-pallets that provides for cooling electronic equipment on a T-pallet facing the sun without the drawbacks of steerable radiators or thermal storage systems using phase-change material.
Additional advantages of the present invention will be set forth in part in the description that follows and in part will be obvious from that description or can be learned by practice of the invention. The advantages of the invention can be realized and obtained by the apparatus particularly pointed out in the appended claims.